Pigment-Dyeing Method

ABSTRACT

Pigment-dyeing method for individualised textile fibres or textile supports obtained from the fibres consisting of pre-treating the fibres or the support with at least one polymer, then dying the thus pre-treated fibres or support using pigments, characterised in that the polymer is a vinylamine-based (co)polymer.

FIELD OF THE INVENTION

The invention relates to the textiles domain. More precisely, the invention relates to a novel pigment-dyeing method for textile materials by exhaustion.

BACKGROUND OF THE INVENTION

There are two types of products to colour textile materials: the dyes and the pigments.

The dyes are water-soluble compounds. They can be of different classes, such as direct, reactive, sulphur-based, indigo, basic or acidic. The benefit of the dye is that it penetrates the fibre itself. However, using dyes requires additional rinsing steps, which result in highly polluted water with residual dyes, which can cause ecological problems. Moreover, the colouration process is long and requires large quantities of water and energy.

The pigments are chemically inert, are not soluble in water nor in most of the solvents currently used and don't have an affinity for the fibres. Consequently, they cannot penetrate in the fibre like the dye but remain on the surface only. Their use involves the use of binders, generally of the thermoplastic elastomer type, and the use of fixing agents in order to obtain high quality of resistance of the colours to wet tests.

In the textile industry the pigments are certainly the simplest and most used method for colouring textile materials because they offer many benefits:

-   -   a versatile aspect (all fibres),     -   their capabilities of preserving the environment (low amounts of         waste, no subsequent washing, etc.),     -   their good resistance to light, water and solvents,     -   a wide choice of shades,     -   less expensive application method.

It is known to a person skilled in the art that pigment-dyeing by exhaustion is possible by providing substantivity to the pigments by adding a cationic charge auxiliary which provides affinity to the pigments for the fibre. The textile supports are then cationised before the dyeing step itself.

A person skilled in the art have several cationisation agents at its disposal which allow improving the affinity of the fibre with the pigments.

The patent U.S. Pat. No. 5,006,129 describes a method of pigmenting which includes a textile pre-treatment step with a cationisation agent which includes a quaternary ammonium group. The patent U.S. Pat. No. 5,252,103 claims a method of pigmenting using cationic components that include a quaternary ammonium group. Among the components used, one can cite acrylamide/2-(Methacryloyloxy)ethyl trimethylammonium chloride copolymer.

However, the prior art is not completely satisfactory. The current problem is thus finding a pigment-dyeing method that allows dyeing cellulose-based textile supports or a combination of cellulose and synthetic fibres with the following advantages:

-   -   complete exhaustion of the dye baths,     -   extremely high colour yields,     -   high affinity of the pigment for the fibre,     -   extremely short method times and low water volumes needed,     -   extremely high solidity of the colours during wet tests,     -   very low DCO and DBO5 charges in the effluents.

SUMMARY OF THE INVENTION

The problem that the invention purports to solve is to provide a novel pigment-dyeing method for textile materials by exhaustion showing the above-mentioned advantages while eliminating the disadvantages of the prior art.

The applicant has finalised a novel pigment-dyeing method for individualised textile fibres or textile supports obtained from the said fibres consisting of pre-treating the fibres or the support with at least one polymer then of dying the thus pre-treated fibres or support using pigments.

The method is characterised in that the polymer is a VinylAmine-based (co)polymer.

The invention is applicable in particular to the pigment-dyeing of natural and/or synthetic fibres. As natural fibres, it is possible to cite natural cellulose-based vegetable fibres, like cotton, linen, cellulose regenerated fibres like viscose, modal, modified cellulose like acetate and triacetate. We can also mention animal fibres like wool and silk. As synthetic fibres, examples include acrylic-based, modacrylic-based, polyester-based, polyamide-based fibres and their combinations.

The support obtained from the fibres can be a woven, a non-woven or a knitted support.

VinylAmine (co)Polymers (PVA)

The PVA used in the novel method can result from the various methods known by a person skilled in the art. We can cite the PVA resulting from hydrolysis of the homopolymers or copolymers of N vinylformamide, or even the PVA resulting from Hofman degradation.

-   -   PVA resulting from complete or partial hydrolysis of a         (co)N-vinylformamide (co)polymer

In a first step, a N-Vinylformamide (co)polymer (NVF) must be obtained; the NVF having the following pattern:

Consequently, this NVF patter must be converted, by hydrolysis, into VinylAmine:

The hydrolysis can be carried out by an acidic action (acid hydrolysis) or a basic action (basic hydrolysis).

Depending on the added quantity of acid or base, the NVF polymer or copolymer will be partially or completely converted into VinylAmine.

-   -   PVA resulting from Hofman degradation

Hofman degradation is a reaction discovered by Hofmann at the end of the nineteenth century, which allows converting an amide (even an acrylonitrile) into a primary amine by elimination of carbon-dioxide. Details of the reaction mechanism are given below.

In the presence of a base (soda), a proton is pulled off from the amide.

The resulting amidate ion then reacts with the active chloride (Cl₂) of the hypochloride (for example: NaClO which is in balance: 2 NaOH+Cl₂

NaClO+NaCl+H₂O) to result in a N-chloramide. The basic solution (NaOH) pulls off a proton from the chloramide to form an anion. The anion loses a chlorine ion to form a nitrene which undergoes an isocynate transposition.

Through a reaction between the hydroxide ion and isocynate, a carbamate is formed.

R— N═C═Ō+OH⁻→R—NH—CO₂ ⁻

After decarboxylation (elimination of CO2) of the carbamate, a primary amine is obtained.

For the conversion of all or part of the amide groups of an acrylamide (co)polymer in an amine group, two primary factors intervene (expressed in molar ratio). It involves: —Alpha=(alkaline hypohalite and/or alkaline earth metal/acrylamide) and —Beta=(alkaline hydroxide and/or alkaline earth metal/alkaline hypohalogenure and/or alkaline earth metal).

According to certain embodiments the PVA-based (co)polymers can include other ionic and non-ionic monomers.

The non-ionic monomer(s) that can be used within the scope of the invention can be selected, particularly, from the group consisting of water-soluble vinylic monomers in the room. Preferred monomers belonging to this class are, for example, acrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide. Also, it is possible to use N-vinylformamide, and N-vinylpyrrolidone. A non-ionic monomer is preferred over acrylamide.

The cationic monomer(s) that can be used within the scope of the invention can be selected, particularly among the acrylamide, acrylic, vinylic, allelic or maleic monomers that possess a quaternary ammonium group. It is possible to cite, in particular in a non-exhaustive matter, quaternised dimethylaminoethyl acrylate (ADAME) and quaternised dimethylaminoethyl methacrylate (MADAME), dimethylkdiallylammonium chloride (DADMAC), acrylamidopropyltrimethylammonium chloride (APTAC) and methylenebisacrylamidemethacrylamidopropyltrimethylammonium chloride (MAPTAC). The anionic monomers that can be used within the scope of the invention can be chosen in a large group. These monomers can show acrylic, vinylic, maleic, fumaric, allelic groups, and contain a carboxylate, phosphonate, phosphate, sulfate, sulfonate group, or another group with an anionic charge. The monomer can be acid or even in the form of a salt or an alkaline-earth metal or alkaline-metal corresponding to such a monomer. Suitable examples of monomers include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid and highly acidic type monomers, for example having a sulfonic acid or phosphonic acid type group such as 2-acrylamid 2-sulfonic methylpropane acid, vinylsulphonic acid, vinylphosphonic acid, allylsulphonic acid, allylphosphonic acid, sulphonic styrene acid and water-soluble salts of an alkaline metal, an alkaline-earth metal and ammonium.

According to a preferred method the PVA-based (co)polymer results from Hofmann degradation made on a base (co)polymer that includes acrylamide or derivatives.

According to another method of the invention, it is possible to use (co)polymers obtained by Hofman degradation made on a base (co)polymer comprising acrylamide or derivatives and at least one polyfunctional component containing at least three heteroatoms each having at least one mobile hydrogen atom.

Preferably, the polyfunctional component is selected from the group consisting of polyethyleneamine, polyamine, polyallylamine

In a general manner, polymers of the invention do not need development of a particular polymerisation method. Indeed, they can be obtained according to all polymerisation techniques which are well known to a person skilled in the art. They can particularly involve solution polymerisation; gel polymerisation; precipitation polymerisation;

emulsion polymerisation (aqueous or inverse); suspension polymerisation; or micellar polymerisation.

DETAILED DESCRIPTION OF THE INVENTION

Pre-treatment:

In accordance with the invention, the textile material first undergoes a pre-treatment step.

This step consists of putting the textile material into contact with at least one vinylamine-based (co)polymer (PVA) in a bath that contains water.

The PVA (co)polymer is used in dosages from 1 to 10% in weight of the material to be dyed, preferably from 3 to 8%.

The polymer/pigment ratio in weight is between 1:10 and 10:1, preferably between 3:1 and 7:5, and more preferably the ratio is 5:3.

The pre-treatment is generally done at a temperature between 20 and 100° C., preferably between 30 and 80° C. The duration of the pre-treatment is between 1 and 60 minutes, preferably between 5 and 40 minutes.

The bath ratio is the ratio in weight between the total dry material and the total solution constituting the bath. Thus, for example, a bath ratio of 1:10 signifies 10 litres of water for 1 kg of textile material. According to the invention, the bath ratio for pre-treatment is between 1:5 and 1:40, preferably between 1:10 and 1:30.

The pre-treatment step is done at a pH between 3 and 8, preferably the pH is between 5 and 7. The pH is maintained by adding an acid or an acid pH buffering. One can cite, for example, acetic acid, formic acid, ammonium sulfate, sodium carbonate.

After the pre-treatment the bath is emptied. The textile material is rinsed at least once with water at a temperature between 10 and 30° C.

Other components can be introduced during the pre-treatment step. An example might be anti-foam agents and anti-breakage agents.

The pre-treatment can be carried out with the resources known by a person skilled in the art. Preferably, the pre-treatment can be carried out in a dyeing device such as jet flow, over flow, bark, jigger, autoclave, industrial drum, reel and wire dyeing device or skeins.

In order to facilitate the pre-treatment, the textile material can optionally undergo at least one prior step known to a person skilled in the art. An example might be the degreasing, quenching or laundering.

The pre-treatment step can be followed by a softening, stonnage or even bio-polishing of the textile material before the dyeing step.

Dyeing:

In accordance with the invention, after the pre-treatment step, the material undergoes a dyeing step. This step consists of putting the pre-treated textile material into contact with at least one pigment in a bath containing water.

More specifically, the textile material is coloured using the exhaustion pigmentation technique. This technique consists of exhausting the pigment bath by transferring the latter towards the textile material.

The pigment(s) can be introduced in the bath in powder or liquid form. In a preferential manner, the pigments are introduced in liquid form.

In case of liquid form, the pigments are spread in at least one solvent. The concentration of pigments in the solvent is between 10 and 50%, preferably between 25 and 35%. Preferably the solvent is water.

In a general manner, the pigment(s) are added to the bath at 0.1% to 10% in weight of the material to be dyed.

The dyeing is done at a temperature between 20 and 90° C., preferably between 40 and 80° C. The increase in temperature is lower than 10° C. per minute, preferably between 1 and 4° C. per minute.

Once the target temperature is reached, this latter is maintained for 1 to 60 minutes, preferably between 5 and 40 minutes. The bath ratio for dyeing is between 1:5 and 1:40, preferably between 1:10 and 1:30.

After dyeing, the bath is emptied. The textile material is rinsed at least once with water. Preferably the water is at a temperature between 10 and 30° C.

Other components can be present during the dyeing step. An example might be anti-foam agents or anti-breakage agents.

Post-treatment

In order to improve the solidities of the textile material in the wet tests, a post-treatment can optionally be implemented.

This post-treatment consists of adding at least one binder and/or at least one fixing agent.

The binder is a composition that includes pre-polymers of low molecular weight. During the spinning and drying steps (at high temperature), these pre-polymers will react to form a film that entraps and integrates the pigments in the fibre. The binder is used at dosages between 0.1 and 15%, preferably between 1 and 10% in material weight.

The reticulation of the binder is done at a temperature between 50 and 250° C., preferably between 100 and 200° C.

The high temperature exposure lasts between 1 and 20 minutes, preferably between 3 and 10 minutes.

The binder can be acrylate-based, styrene acrylate-based, styrene butadiene based and vinyl-acrylate-based.

The fixing agent reacts to form a three-dimensional network around the fibre at the time of drying.

The fixing agent is used at dosages between 0.1 and 15% preferably between 1 and 10% in material weight.

The fixing agent is used at a temperature between 10 and 90° C., preferably between 20 and 60° C. The pH of the bath is maintained between 3 and 6 per day, by adding an acid or an acid pH buffering.

Once the fixing agent is introduced, the bath is heated. The increase in temperature is lower than 10° C. per minute, preferably between 1 and 4° C. per minute. Once the target temperature is reached, this latter is maintained for 1 to 60 minutes, preferably between 5 and 30 minutes.

The bath ratio is between 1:5 and 1:40, preferably between 1:10 and 1:30.

The fixing agent can be polyisocynate-based, melamine formol-based, dimethyl dihydroxy ethylene urea-based (DMDHEU).

After the post-treatment, the bath is emptied. The textile material is rinsed at least once with water having a temperature between 10 and 30° C.

The post-treatment step can be followed by a softening, stonnage or bio-polishing step of the textile material.

One of the advantages of the invention is in the high rate of exhaustion of the pigments in the dyeing bath, since the baths emptied in the sewage do not have a high load of pigments.

It was unexpectedly discovered that PVA allows higher quality of pigment exhaustion compared to conventional cationisation products. Indeed, it is possible to obtain exhaustion rates higher than 95% for light and medium colours, and higher than 90% for dark colours.

Moreover, without propounding any theory, it would appear that the high pigment/fibre binding avoids a systematic use of binder and/or fixing agent. During subsequent softenings, high quality pigment content was observed, with little or no disgorgement.

The following examples illustrate the invention in a non-exhaustive manner.

EXAMPLES I/ Preparation of the Polymer

Polymer A is obtained by a Hofman degradation reaction on a basic copolymer (20% of active substance) of acrylamide (70% molar) and ramified (MBA: 1000 ppm/active substance) ammonium dimethyldiallyl chloride (DADMAC) (30% molar) modified with a polyethyleneimine polymer (of the Polymin HM type from BASF), at 1% of the active substance. To do this, polyethyleneinmine is combined with DADMAC monomer and MBA in the reactor.

Acrylamide will be incorporated by continuously pouring for 2 hours, in a reactional environment maintained at 85° C. The catalysis will be carried out with SPS and MBS, catalysers well known by a person skilled in the art. The precursor polymer thus obtained shows a viscosity of 5500 cps (LV3, 12 rpm). The Hofman degradation itself is carried out in the same manner as in example 1 of the patent of the applicant PCT/FR/2009/050456. The acrylamide derivative copolymer A thus obtained shows an intrinsic viscosity of 0.72 (25° C., Brookfield LV1, 60 rpm) and a concentration of 8%.

II/ Carrying out of the Method Example 1

A 1:1 ratio of a knit cotton/viscose 50/50 of 150 g/m² is degreased in a winch. The bath ratio is 1:25. 1g/l of a wetting detergent is added to the bath. The bath is then heated and maintained at 60° C. for 25 minutes. The bath is then emptied and the material is then rinsed twice using cold water at 15° C. The pre-treatment is then carried out with a bath ratio of 1:25. The pH is adjusted at 9 with sodium carbonate and 5% in weight of polymer A material is added. The bath is heated and maintained at 60° C. for 30 minutes. The bath is emptied and the material is then rinsed twice using cold water at 15° C. The dyeing is then carried out in a bath ratio of 1:25. In the bath, which has an initial temperature of 15° C., 3% of 15/3 blue pigment is added. The heat is then set to 60° C., in increments of 3° C. per minute. The temperature is maintained for 30 minutes. The bath is emptied and the material is then rinsed twice using cold water 15° C. The treated materials is then softened with a nano-silicone emulsion type softener dosed at 2% for 15 minutes, temperature of the bath set to 40° C., pH 5 adjusted with acetic acid.

Example 2

100% cotton material trousers twill 3/1 205 g/m² are firstly desized in an industrial drum machine. The bath ratio is 1:10. The pH is adjusted to 6 with acetic acid. 3 g/l of an amylase is added to the bath. The desizing is done at 60° C. for 20 minutes. The material is then cold rinsed twice using water at 15° C. The trousers are then cationised in a bath ratio of 1:10, at pH 6 adjusted with acetic acid. 5% in weight of the polymer material is added to the bath. The bath is then heated and maintained at 60° C. for 30 minutes. The material is then cold rinsed twice using water 15° C. The dyeing is then carried out in a bath ratio of 1:10. In the bath, which has an initial temperature of 15° C., 3.5% of 7 green pigment is added. The heat is then set to 60° C., in increments of 3° C. per minute. The temperature is maintained for 40 minutes. The bath is then emptied and the material is then cold rinsed twice using water 15° C. Stonnage is then carried out on the material for 20 min at a bath ratio of 1:10 at pH 4.5 with 1.5% of acid cellulase. The bath is emptied and the material is then cold rinsed twice using water 15° C. The materials is then softened with 1% of silicone micro emulsion and 1% of fatty acid for 15 minutes, temperature of the bath set to 40° C., pH 6 adjusted with acetic acid, the material is then squeezed and dried.

Example 3

A 100% cotton poplin cloth 105 g/m² pre-desized is firstly whitened on an overflow dyeing machine with a bath ratio of 1:20. The following products are added to the whitening bath: anti-foam, anti-breakage, oxygenated water stabiliser, oxygenated water, caustic soda. The bath is then heated at 98° C. for 30 minutes. The bath is then cooled to 70° C. and the material neutralised at pH 7 with acetic acid. The bath is then emptied and the material is then cold rinsed once. The cationisation is then carried out in a bath ratio of 1:20 at pH 5.5 adjusted with a pH acid buffer. 5% in weight of a PVA cationisation agent, an anti-breakage agent and an anti-foam agent are added to the bath. The bath is then heated and maintained at 60° C. for 30 minutes. The material is then rinsed twice using cold water at 15° C. The dyeing is then carried out in a bath ratio of 1:20 at pH 5.5. 2% of orange pigment 34, 1% of yellow pigment 83, an anti-foam agent, an anti-breakage agent and a dispersant are added to the water at a temperature of 15° C. The heat is then set to 70° C., in increments of 1° C. per minute. The temperature is maintained for 20 minutes. At 70° C. an acrylic binder is added to the bath and dosed at 5%. The bath is then emptied and the material is then cold rinsed. The material is then softened with a silicone hydrophilic emulsion type softener dosed at 2% for 20 minutes, bath temperature at 40° C., pH 5 adjusted with an acid buffer.

Example 4

The cotton cloth of example 3 is whitened continuously, rolled and dried. The cloth is then foulard finished on a sizing foulard in a bath containing 75 g/l of polymer A, at pH 6. The dye exhaust percentage is maintained at 60-80%, the material is then dried on a drying stenter at 100-120° C. The cloth thus treated and is then dyed according to the same protocol described in example 3.

Example 5 Counter-example

Example 3 is reproduced identically by replacing the polymer A by the PRECAT 3005 (homopolymer of chloromethyled MADAME) distributed by CHT, R BEITLICH GMBH used at 3%.

The bath exhaustion, colours and friction solidity inspections are carried out.

III/ Assessment Tests

Assessment of the Rate of Exhaustion:

At the end of each dyeing a bath sample is taken in order to control the rate of exhaustion E (%) of the dyeing bath pigments using a visible UV spectrophotometer (spectral range from 190 to 900 nm, quartz cell of 10 mm) This latter is calibrated using successive dilutions of the initial coloured pigment solution.

E(%)=Ci−Cf/Ci*100.

Assessment of the Dry and Wet Solidities:

A final cloth sample is taken in order to inspect the dry and wet friction solidities following the standard NF EN ISO 105-X12(2003) and using a crockmeter. The colour fadings on the cotton samples are assessed using the gray scale and the ISO standard 105-A03(2005).

Assessment of the Colour:

The final cloth colour is compared in relation with the standard using a spectrophotometer under the D65 illuminate and at an angle of 10 degrees. The colour differences are determined by calculating the Delta E (CIE 2000) and coloured forces (%) compared to the counter-example.

Results

Friction solidities Tests dry humid E (%) FC (%) Example 1 4-5 4 93.5 108.6 Example 2 4 3-4 91.2 112.4 Example 3 4-5 4 92.8 110.5 Example 4 4-5 4 90.8 109.8 Example 5 3-4 3 86.4 100

It can be observed that the novel cationisation pre-treatment allows obtaining, compared with a conventional method:

-   -   1 to 2 points in result on the dry and humid friction         solidities,     -   an increase in the rate of exhaustion E(%) of the pigments from         5 to 10%,     -   an increase in the FC tone levels (%) from 5 to 15%. 

1. A pigment-dyeing method for individualised textile fibres or textile supports obtained from the fibres consisting of pre-treating the fibres or the support with at least one polymer, then dying the pre-treated fibres or support using pigments, characterised in that the polymer is a vinylamine-based (co)polymer.
 2. The method according to claim 1, characterised in that the vinylamine-based (co)polymer results from a total or partial hydrolysis of a N-vinylformamide (co)polymer.
 3. The method according to claim 1, characterised in that the vinylamine-based (co)polymer results from a Hofman degradation reaction carried out on a base (co)polymer comprising acrylamide or derivatives.
 4. The method according to claim 3 characterised in that the base (co)polymer further comprises at least one polyfunctional component comprising at least three heteroatoms that each have at least one mobile hydrogen atom.
 5. The method in accordance with claim 4, characterised in that the polyfunctional component is selected from the group consisting of polyethyleneimine, polyamine, and polyallylamine.
 6. The method according to claim 1, characterised in that the (co)polymer represents from 1 to 10% in weight of the material to be dyed.
 7. The method according to claim 1, characterised in that the polymer/pigment ratio is between 1:10 and 10:1.
 8. The method according to claim 1, characterised in that the pigment represent 0.1% to 10% in weight of the material to be dyed.
 9. The method according to claim 1, characterised in that the weight ratio between total dry material and total solution is between 1:5 and 1:40.
 10. The method according to claim 1, characterised in that the (co)polymer represents from 3 to 8% in weight of the material to be dyed.
 11. The method according to claim 1, characterised in that the polymer/pigment ratio is between 3:1 and 7:5.
 12. The method according to claim 1, characterised in that the polymer/pigment ratio is equal to 5:3.
 13. The method according to claim 1, characterised in that the weight ratio between total dry material and total solution is between 1:10 and 1:30. 